Quarry owner says blasting didn't cause tremor

Joseph RuzichSpecial to the Tribune

A construction material company acknowledged that it was blasting at its quarry in McCook on Monday, but officials deny the activity caused a tremor that sent shock waves through the western suburbs and caused some minor damage.

Jeff Sieg, a spokesman for Lehigh Hanson Inc., said Tuesday that the company did a routine blast at 12:35 p.m. well below regulatory limits. He added that a separate seismic event occurred about seven seconds after the blast.

"It is baffling to us," Sieg said. "There is no obvious connection except that they were seven seconds apart."

He said equipment the company owns detected the separate seismic event.

However, Julie Dutton, a geophysicist at the U.S. Geological Survey, said the agency is standing by its opinion that a quarry blast caused the tremor.

"The waveforms generated from the event indicate that it was a blast from a quarry in the area," said Dutton, who reiterated that the occurrence was not considered an earthquake.